How do I make a border or color a whole page on pages?

From the Help menu:

1. Click Shape in the toolbar, then choose the square or rounded square.
2. Drag the selection handles until the border is the size you want.
3. Click the Arrange button near the top of the sidebar.If you don’t see a sidebar, or it doesn’t have an Arrange button, click the Paintbrush in the toolbar.
4. In the Object Placement section, click Stay on Page.
5. Click the Text Wrap pop-up menu and choose None.
6. Click the Style button near the top of the sidebar, then do any of the following:
   • Apply a shape style: Click one of the shape styles at the top of the sidebar to quickly apply a fill color, gradient, shadow, or other attribute.
   • Change the border line: Click the Border pop-up menu and choose Line, then choose a line style from the pop-up menu below it. Click the color well to change the color of the line, and click the arrows to change the thickness of the line.
   • Use a picture frame style: Click the Border pop-up menu and choose Picture Frame, then choose a picture frame style from the pop-up menu below it.
   • Change the opacity of a fill color: Drag the opacity slider to make a fill color or image more or less opaque.
7. To use the border on every page in a section, choose Arrange > Section Masters > Move Object to Section Master (from the Arrange menu at the top of your screen).The border is applied only to pages in that section. If your document has more than one section and you want the border to appear on every page in the document, add the border to the section master for each section.